esphome::runtime_image::ImageDecoder Class Reference

Class to abstract decoding different image formats. More...

#include <image_decoder.h>

Inheritance diagram for esphome::runtime_image::ImageDecoder:

Public Member Functions
	ImageDecoder (RuntimeImage *image)
	Construct a new Image Decoder object.
virtual	~ImageDecoder ()=default
virtual int	prepare (size_t expected_size)
	Initialize the decoder.
virtual int	decode (uint8_t *buffer, size_t size)=0
	Decode a part of the image.
bool	set_size (int width, int height)
	Request the image to be resized once the actual dimensions are known.
void	draw (int x, int y, int w, int h, const Color &color)
	Fill a rectangle on the display_buffer using the defined color.
virtual bool	is_finished () const
	Check if the decoder has finished processing.

Protected Attributes
RuntimeImage *	image_
size_t	expected_size_ = 0
size_t	decoded_bytes_ = 0
double	x_scale_ = 1.0
double	y_scale_ = 1.0

Detailed Description

Class to abstract decoding different image formats.

Definition at line 17 of file image_decoder.h.

Constructor & Destructor Documentation

ImageDecoder()

esphome::runtime_image::ImageDecoder::ImageDecoder ( RuntimeImage * image )

inline

Construct a new Image Decoder object.

Parameters

image

The RuntimeImage to decode the stream into.

Definition at line 24 of file image_decoder.h.

~ImageDecoder()

virtual esphome::runtime_image::ImageDecoder::~ImageDecoder ( )

virtualdefault

Member Function Documentation

decode()

virtual int esphome::runtime_image::ImageDecoder::decode ( uint8_t * buffer, size_t size )

pure virtual

Decode a part of the image.

It will try reading from the buffer. There is no guarantee that the whole available buffer will be read/decoded; the method will return the amount of bytes actually decoded, so that the unread content can be moved to the beginning.

Parameters

buffer	The buffer to read from.
size	The maximum amount of bytes that can be read from the buffer.

Returns

int The amount of bytes read. It can be 0 if the buffer does not have enough content to meaningfully decode anything, or negative in case of a decoding error.

Implemented in esphome::runtime_image::BmpDecoder, esphome::runtime_image::JpegDecoder, and esphome::runtime_image::PngDecoder.

draw()

void esphome::runtime_image::ImageDecoder::draw	(	int	x,
		int	y,
		int	w,
		int	h,
		const Color &	color )

Fill a rectangle on the display_buffer using the defined color.

Will check the given coordinates for out-of-bounds, and clip the rectangle accordingly. In case of binary displays, the color will be converted to binary as well. Called by the callback functions, to be able to access the parent Image class.

Parameters

x	The left-most coordinate of the rectangle.
y	The top-most coordinate of the rectangle.
w	The width of the rectangle.
h	The height of the rectangle.
color	The fill color

Definition at line 18 of file image_decoder.cpp.

is_finished()

virtual bool esphome::runtime_image::ImageDecoder::is_finished ( ) const

inlinevirtual

Check if the decoder has finished processing.

This should be overridden by decoders that can detect completion based on format-specific markers rather than byte counts.

Reimplemented in esphome::runtime_image::BmpDecoder.

Definition at line 81 of file image_decoder.h.

prepare()

virtual int esphome::runtime_image::ImageDecoder::prepare ( size_t expected_size )

inlinevirtual

Initialize the decoder.

Parameters

expected_size

Hint about the expected data size (0 if unknown).

Returns

int Returns 0 on success, a {

See also

DecodeError} value in case of an error.

Reimplemented in esphome::runtime_image::JpegDecoder, and esphome::runtime_image::PngDecoder.

Definition at line 33 of file image_decoder.h.

set_size()

bool esphome::runtime_image::ImageDecoder::set_size	(	int	width,
		int	height )

Request the image to be resized once the actual dimensions are known.

Called by the callback functions, to be able to access the parent Image class.

Parameters

width	The image's width.
height	The image's height.

Returns

true if the image was resized, false otherwise.

Definition at line 11 of file image_decoder.cpp.

Field Documentation

decoded_bytes_

size_t esphome::runtime_image::ImageDecoder::decoded_bytes_ = 0

protected

Definition at line 92 of file image_decoder.h.

expected_size_

size_t esphome::runtime_image::ImageDecoder::expected_size_ = 0

protected

Definition at line 91 of file image_decoder.h.

image_

RuntimeImage* esphome::runtime_image::ImageDecoder::image_

protected

Definition at line 90 of file image_decoder.h.

x_scale_

double esphome::runtime_image::ImageDecoder::x_scale_ = 1.0

protected

Definition at line 93 of file image_decoder.h.

y_scale_

double esphome::runtime_image::ImageDecoder::y_scale_ = 1.0

protected

Definition at line 94 of file image_decoder.h.

---

The documentation for this class was generated from the following files:

• esphome/components/runtime_image/image_decoder.h
• esphome/components/runtime_image/image_decoder.cpp